function setCanvas(map) {
    const canvas = document.createElement("canvas");
    let size = 40;
    canvas.width = size;
    canvas.height = size;
    let radius = size / 4;  //10;
    let increase = true;
    let ctx = canvas.getContext("2d");
    function draw() {
        ctx.clearRect(0, 0, size, size);
        /* 第一个圆 */
        ctx.beginPath();
        ctx.arc(size / 2, size / 2, radius, 0, Math.PI * 2);
        ctx.closePath();
        ctx.fillStyle = "#ff2d51";
        ctx.fill();
        /* 设置第二个圆 */
        ctx.beginPath();
        ctx.arc(size / 2, size / 2, 8, 0, Math.PI * 2);
        ctx.closePath();
        ctx.fillStyle = "#0D5EFF";
        ctx.fill();
        if (radius > 14) {
            increase = false;
        }
        if (radius < 10) {
            increase = true;
        }
        if (increase) {
            radius++;
        } else {
            radius--;
        }
        setTimeout(draw, 100);
        map.render(); //让地图重新渲染一下
    }
    draw();
    return canvas;
}